This research will examine three aspects of the thiol-disulfide interchange reaction. The first comprises studies of the physical-organic chemistry of this reaction. This work will use the thiol-disulfide interchange reaction to examine the mechanistically important concept of "effective intramolecular concentration" and to explore intermolecular recognition in a mechanistically well-defined type of reaction. The second will apply the thiol-disulfide interchange reaction to several problems in biochemistry: development of redox buffer systems and redox-active membrane systems, estimation of the properties of disulfide groups in polypeptides, prevention of protein autoxidation. The third will explore a new approach to development of enzyme inhibitors based in thiol-disulfide interchange, and prepare several disulfide-containing polymers of potential use in biochemistry. This program work will provide mechanistic concepts useful in mechanistic biochemistry and enzymology, generate reagents and techniques useful in protein and polypeptide chemistry, test a new approach to drug development, and provide new analytical techniques useful in biochemical systems.